JPH0263055A - Polymer composition sensitive for radiation - Google Patents

Abstract

PURPOSE:To cause a crosslinking reaction for irradiation of radiation efficiently, and to form a fine resist pattern with high precision and high sensitivity by forming a polymer having a propargyl group, etc., and a sensitizing group in the side chain. CONSTITUTION:The title polymer (A) has a propargyl group and/or a substituted propargyl group together with a sensitizing group in a side chain, which is a (co)polymer prepd. by adding a propargyl group and/or a substituted propargyl group together with a sensitizing group to a reactive group of a (co)polymer having reactive groups such as OH group, COOH group, etc. Examples for such reactive polymer are polyacrylic acid, polymethacrylic acid, etc. Further, the polymer (A) has a sensitizing group, such as naphthyl group, anthranyl group, etc. Thus, a polymer compsn. having high sensitivity for radiation is obtd. which can form fine resist pattern with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a radiation-sensitive polymer composition, and more particularly, it relates to a radiation-sensitive polymer composition that is sensitive to visible light, ultraviolet rays, deep ultraviolet rays, electron beams, X-rays, ion beams, and molecular beams. The present invention relates to a radiation-sensitive polymer composition suitable as a negative resist sensitive to radiation such as γ-rays, synchrotron radiation, and proton beams.

[Prior Art] Conventionally, in the manufacture of semiconductor integrated circuits, etc., a fine resist pattern is formed by coating a resist on a substrate, partially irradiating it with radiation, and developing it. Etching of the substrate portion is performed.

The resist used in this series of radiation patterning processes has high sensitivity to radiation, can form fine resist patterns with high precision, and has high resistance to etching. It is necessary.

[Problems to be solved by the invention] In recent years, it has been reported that a radiation-sensitive polymer composition comprising a polymer having a propargyl group and a photoradical initiator is crosslinked by irradiation (Kobunshi Papers Collection 3
Vol. 7, pp. 249-254, 1980, JP-A-62-2
53152).

The radiation-sensitive polymer compositions have the disadvantage that they become significantly less sensitive to radiation in the presence of oxygen, for example in air.

[Means for Solving the Problems] The present invention comprises: (1) a polymer having a propargyl group and/or a substituted propargyl group and a sensitizing group in the side chain (hereinafter abbreviated as "polymer A"); A radiation-sensitive polymer composition characterized by: and (ii) a polymer obtained by halogenating a polymer having a propargyl group and a substituted propargyl group in the side chain (hereinafter abbreviated as "polymer B"). ) A radiation-sensitive polymer composition is provided.

In the present invention, Polymer A is a (co)polymer having reactive groups such as hydroxyl groups and carboxyl groups (hereinafter abbreviated as "reactive polymer").
or a substituted propargyl group (hereinafter referred to as "propargyl group, etc.") and a sensitizing group (co-)
It is a polymer.

Here, the reactive polymers include polyacrylic acid, polymethacrylic acid, poly(hydroxystyrene), poly(hydroxy-α-methylstyrene), polyamic acid, polyamide having a hydroxyl group, polyester having a hydroxyl group, polysaccharide, casein. Preferably, polyacrylic acid, polymethacrylic acid, poly(hydroxystyrene), poly(α-methylhydroxystyrene), etc.
Examples include acrylic polymers and styrene polymers having carboxyl groups or hydroxyl groups in their side chains.

In addition, the propargyl group, etc. that polymer A has has the formula
R' C=-C-CR2R3- (wherein, R1, R2
and R3 are the same or different, a hydrogen atom, a methyl group,
It represents an alkyl group having 1 to 4 carbon atoms such as an ethyl group, a propyl group, a butyl group, a phenyl group, or a benzyl group. ), specifically, propargyl group, 3
-methylpropargyl group, 1-methylpropargyl group,
1,1-dimethylpropargyl group, 1,1-dimethyl-
3-methylpropargyl group, 3-ethylpropargyl group,
1-ethylpropargyl group, 1,1-diethylpropargyl group, 3-phenylpropargyl group, 1-phenylpropargyl group, 1,1-diphenylpropargyl group, 3
Examples include -benzylpropargyl group, 1-benzylpropargyl group, and 1-phenyl-3-methylpropargyl group.

In Polymer A, these propargyl groups usually account for 5 to 9 of the total repeating units of the reactive polymer.
9%, preferably 40-85%. If the amount of propargyl groups provided is less than 5%, the crosslink density will be low when the resulting polymer A is crosslinked by radiation.

Furthermore, polymer A has a sensitizing group.

Here, the sensitizing group includes aromatic condensed ring groups such as naphthyl groups and anthranyl groups, and carbon atoms such as methyl, ethyl, propyl, and butyl groups having these aromatic condensed ring groups as substituents. Aromatic ketone groups such as alkyl groups of numbers 1 to 4, benzoylphenyl groups, anthraquinonyl groups, and carbon atoms such as methyl groups, ethyl groups, propyl groups, butyl groups having these aromatic ketone groups as substituents Examples include alkyl groups of numbers 1 to 4.

In Polymer A, this sensitizing group is usually added to 1 to 30%, preferably 5 to 15% of the total repeating units of the reactive polymer.

As a method for introducing a propargyl group etc. into a reactive polymer, a reactive polymer and propargyl bromide, propargyl chloride, which can have an alkyl group having 1 to 4 carbon atoms as a substituent,
with propargyl halides such as propargyl fluoride and propargyl iodide in the presence of a basic catalyst.
A method for obtaining a polymer (hereinafter abbreviated as "polymer A-IJ") in which some of the reactive groups of the reactive polymer are propargylated by reacting at .degree. C. can be mentioned.

In this reaction, the amount of propargyl halide used in the reactive polymer is preferably 0.05 to 2 mol, particularly preferably 0.5 to 2 mol, per gram equivalent of the reactive group of the reactive polymer. be. If the amount of propargyl halide used is less than 0.05 moles, the produced polymer A
-I has a small amount of propargyl groups, etc., and sufficient radiation sensitivity cannot be obtained.

In addition, examples of the basic catalyst include nitrogen-containing organic compounds such as pyridine, triethylamine, and 1,8-diazabicyclo-[5,4°0]-undecene-7 (hereinafter abbreviated as rDBUJ). The amount used is preferably 1 to 20 mol, particularly preferably 1 to 5 mol, per 1 mol of propargyl halide.

In the reaction to obtain the polymer A-I, the basic catalyst itself can be used as a reaction solvent, but if the viscosity of the reaction system is high, a diluting solvent can also be used.

Examples of the diluting solvent used here include aprotic solvents such as dimethylformamide and dimethyl sulfoxide, ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone, and cyclic ethers such as dioxane and tetrahydrofuran.

After the reaction is completed, the reaction system is neutralized using acetic acid or the like, and the polymer A-1 is precipitated and recovered using a large excess of water, isopropanol, or a poor solvent such as alcohol. Note that the recovered polymer A-1 can be purified by dissolving it in a good solvent such as tetrahydrofuran or dioxane, passing away insoluble matter, and then reprecipitating it with a poor solvent.

As a method for further introducing a sensitizing group into the polymer A-I obtained in this way, polymer A-I and 1-chloronaphthalene, 2-bromomethylanthracene, 2-bromomethylanthraquinone, etc. General formula W-Z (wherein, W represents a halogen atom such as a fluorine atom, an iodine atom, a chlorine atom, a bromine atom, or a halogenated alkyl group having 1 to 4 carbon atoms, and Z represents a sensitizing group as described above) ) is dissolved in the same solvent as in the synthesis of polymer A-1, and heated at usually 40 to 100°C in the presence of a basic catalyst as in the synthesis of polymer A-1. Examples include a method of heating and reacting, and recovery and purification of Polymer A can be performed in the same manner as in the case of Polymer A-I.

The polymer A can also be used by reacting it with a halogen in the same manner as in the production of the polymer B described later to halogenate the main chain or side chain of the polymer A.

In the present invention, Polymer B is prepared by combining Polymer A-1 and a halogen such as chlorine, bromine, iodine, or fluorine in a halogenated solvent such as dichloromethane at a temperature usually below 0°C, preferably -
It can be synthesized by reacting at 5 to -10°C.

The amount of halogen used for the polymer A-1 is per gram equivalent of propargyl group, etc., which the polymer A-1 has,
Preferably 0.5 to 3 mol, particularly preferably 1 to 2.5 mol
It is a mole. If the amount of halogen is less than 0.5 mol,
The amount of halogen B in the resulting polymer decreases, making it impossible to obtain sufficient radiation sensitivity.

After the reaction is completed, polymer B is precipitated and recovered using a hydrocarbon solvent such as n-hexane or n-hebutane. Moreover, the recovered polymer B can be purified by dissolving it in a good solvent such as tetrahydrofuran and reprecipitating it in a poor solvent.

The amount of halogen contained in Polymer B is generally 0.02 to 4 gram equivalents, preferably 0.2 to 2 gram equivalents, per 1 gram equivalent of all repeating units of Polymer B.

Furthermore, in the present invention, when synthesizing the polymer A or B, a polymer having a carboxyl group in the side chain, such as polyacrylic acid or polymethacrylic acid, is used as a reactive polymer, and a propargyl 5% or more, preferably 20% or more of the carboxyl groups remain after the introduction of the groups, sensitizing groups and/or halogen atoms, and the remaining carboxyl groups are neutralized with a basic compound to make them water-soluble. You can also.

Basic compounds used to neutralize carboxyl groups include:
Inorganic alkalis such as potassium hydroxide and sodium hydroxide, N (CH3)40H1HOCH2CH2N (CH
3) Quaternary ammonium salts such as 5-OH, ammonia,
Amines such as trimethylamine can be used. This neutralization reaction is usually performed by adding a basic compound dissolved in methanol, ethanol, etc. to polymer A or B dissolved in the same solvent as used in the synthesis of polymer A-1, and reacting at room temperature. Do it by doing this. After the reaction is completed, the reaction solution is made water-soluble with ether or the like, and the polymer A or B is precipitated and recovered.

In the composition of the present invention, the polymer A or B can be used in a solvent such as an aromatic solvent such as chlorobenzene, xylene, ethylbenzene, toluene, anisole, a ketone solvent such as cyclohexanone or methyl ethyl ketone, chloroform, carbon tetrachloride, trichloroethane, etc. chlorinated solvents,
Alternatively, polymer A or B is dissolved in a glycol solvent such as methyl cellosolve acetate or diglyme. Here, the concentration of polymer A or B in solution is generally 5 to 30% by weight. In addition, when the polymer A or B is water-solubilized, water can also be used as a solvent.

A stabilizer (anti-aging agent) or the like can be added to the composition of the present invention, if necessary.

Examples of the stabilizer include phenolic compounds such as hydroquinone, methoxyphenol, p-t-butylcatechol, 2,2'-methylenebis(6-t-butyl-4-ethylphenol), benzoquinone, p-tolquinone, p- -quinones such as xyloquinone, phenyl-α-
Amines such as naphthylamine, P,P'-diphenylphenylenediamine, and dilaurylthiodipropionate, 4,4-thiobis(6-t-butyl-3-methylphenol), 2,2'-thiobis(4- methyl-6-t-butylphenol), 2-(3,5-di-t
Sulfur compounds such as -butyl-4-hydroxyanilino') -4,6-bis(N-octylthio)-δ-triazine are mentioned, and the amount added is determined based on the polymer A or polymer B of the present invention. , usually 0.5 to 5% by weight.

When the composition of the present invention is used as a resist, the composition prepared as described above is applied onto a substrate such as a silicon wafer using a spinner, dried to form a film, and then coated on the film. By irradiating radiation in a predetermined pattern shape, the polymer A in the radiation irradiated area is
Alternatively, a negative resist pattern is obtained by crosslinking B and removing the uncrosslinked portion by development.

Here, the developer includes ketone solvents such as methyl ethyl ketone, acetone, and cyclohexanone, ester solvents such as butyl acetate and ethyl acetate, glycol ester solvents such as cellosolve and methyl cellosolve, and cyclic ether solvents such as dioxane and tetrahydrofuran. ,
Alternatively, mixed solvents of these solvents and the solvent used for preparing the composition of the present invention, alcoholic solvents such as ethanol and isopropanol, or aliphatic solvents such as n-hexane and n-heptane can be exemplified. .

Furthermore, if the polymer A or B is water-solubilized, water can be used as the developer. The substrate on which the resist pattern has been formed is dried and heat treated at 50 to 200°C, and subjected to etching and other treatments.

Example 1 (1) Polyacrylic acid (30°C, 0.5 g/d in DMF
Propargyl bromide 17.3 g (monomer unit 0.24 mol) was dissolved in dimethyl sulfoxide 200@1.
3g (0.14mol) and DBU40, 19g
(0.26 mol) was added and reacted at 50°C for 1 hour. Next, 100 d of acetic acid was added to the reaction solution to neutralize it,
The precipitated polymer was recovered by pouring into water, and reprecipitated once with tetrahydrofuran and water, once with tetrahydrofuran and ether, and dried under reduced pressure at 50°C.
10.3 g of a polymer A-I containing 0% propargyl groups was obtained. This polymer A-1 is referred to as polymer (2).

(2) Dissolve 1 g of the polymer ■ synthesized in (1) in dimethylformamide 5-, and add 645 g (4
, 2 mmol) was added. To this solution, 0.105 g (0.35 mmol) of 2-bromomethylanthraquinone (BMAQ) dissolved in 5 ml of dimethylformamide was added, and methanol 5- was further added, and the mixture was reacted at 50° C. for 24 hours. After the reaction was completed, the reaction solution was neutralized by adding 5-acetic acid and poured into a large amount of water to recover the precipitated polymer. Further, reprecipitation purification was performed once using tetrahydrofuran and water and once using tetrahydrofuran and ether, and 5
It was dried under reduced pressure at 0° C. to obtain a polymer A in which 60% of the carboxyl groups of polyacrylic acid had propargyl groups and 3.2% had methylanthraquinonyl groups. This polymer is referred to as Polymer (2).

(3) Dissolve 0.1 g of the polymer ■ obtained in (2) in methyl cellosolve to make a 5% by weight solution, and apply it on a copper plate using a spin code method to a dry film thickness of 0.5 μm. It was air-dried for 1 hour. After drying, place Kodak Step Tablet 2 on top of this and hold it from a distance of 3 cm.
The film was irradiated with light using a 250 W ultra-high pressure mercury lamp for 5 minutes, and then developed using a 15/85 (weight ratio) mixture of methyl ethyl ketone/ethyl acetate as a developer for 5 minutes, and the number of insolubilization stages was determined to be 12.

The step tablet used here is formed by arranging multiple parts with different transmittances so that the intensity of the irradiated radiation changes stepwise, and the level of transmittance is expressed by a numerical value (number of steps). , the number of insolubilization stages indicates that the larger the number, the smaller the amount of radiation irradiation required for insolubilization.

Example 2 (1) 1 g of the polymer ■ synthesized in Example 1 (2) was dissolved in 50 ml of tetrahydrofuran, and 35.4 mm of a methanol solution of potassium hydroxide at a concentration of 0.1N was added to neutralize the carboxyl groups. It was peaceful. This solution was poured into 300°C ether, the precipitated polymer was collected, and the solution was heated to 50°C.
1.07 g of Polymer A was dried under reduced pressure to convert the entire amount of carboxyl groups remaining in Polymer 2 into carboxylic acid potassium salt.
Obtained. The reduced viscosity of this polymer A is 2. 02de/g
(30°C, 0.5 g/de, water). This polymer is referred to as Polymer (2).

(2) 0.1 g of the polymer synthesized in (1) was dissolved in water to make a 5% by weight solution, which was applied onto a copper plate using a spin cord method to a dry film thickness of 10 μm, and dried under reduced pressure for 1 hour. . Next, Kodak Step Tablet Nα2 was placed on top of this, irradiated with light for 2 minutes from a distance of 3 cm in the air using a 250W ultra-high pressure mercury lamp, and immersed in water for 5 minutes to develop, and the number of insolubilization stages was determined. It was 16 steps.

Comparative Example 1 Polymer ■ synthesized in Example 1 (1) was dissolved in methyl hetamine to give a concentration of 5% by weight, and 2-methylanthraquinone was added and dissolved in varying amounts as a sensitizer. Light was irradiated in the same manner as in Example 1, and acetone/
Developed with a mixed solvent of methanol = 1/1 (volume ratio),
The number of insolubilization stages was determined.

The highest sensitivity was obtained when the amount of 2-methylanthraquinone added was 0.06 gram equivalent per gram equivalent of all repeating units of Polymer 1, but the number of insolubilization stages at this time was 4, and the polymer side chain The sensitizing effect was lower than that of Example 1, in which a sensitizing group was introduced into the sample.

Comparative Example 2 In Comparative Example 1, the number of insolubilization stages was determined in the same manner as in Comparative Example 1 except that no sensitizer was added, and it was found to be 0 stages.

Example 3 (1) Polymer synthesized in Example 1 (1) ■ 0.60
After dissolving 6 g in dichloromethane and cooling to below 0°C, 0.6 g of bromine was dissolved. A solution of 5@f (9.8 mmol) dissolved in dichloromethane 2- was added dropwise and reacted for 3 hours. After the reaction was completed, the reaction solution was poured into 50 aff of n-hexane, and the precipitated polymer was collected by decantation.
Reprecipitate once with tetrahydrofuran-water system and once with tetrahydrofuran-〇-hexane system, and dry under reduced pressure to obtain 0.9
1 g of purified polymer B was obtained. The reduced viscosity of this polymer B is 0.26 dfl/g (0.5 g/dfl, 30°C, D
MF), and contained 1.9 gram equivalents of bromine per 1 gram equivalent of all repeating units possessed by Polymer B. The obtained Polymer B was bound with Polymer ①.

(Polymer ① obtained in 21(1) was dissolved in cellosolve acetate to make a solution with a concentration of 15% by weight, and a dry film thickness of 0.5
It was coated in a thickness of μm.

After pre-baking on a hot plate at 90°C for 2 minutes, proximity was measured using palladium Lα rays as X-rays in a helium atmosphere and varying the irradiation dose through a mask pattern made of a 087 μm thick boron nitride film with a total absorber. X-ray irradiation was performed with a gap of 20 μm. After irradiation,
The film was developed by immersion in ethyl cellosolve for 1 minute, rinsed with methyl ethyl ketone/isopropyl alcohol for 1 minute, dried, and the remaining film rate and resolution were measured. The irradiation dose at which the residual film rate is 50% is 60 mJ/crB, and the resolution is 0.8
It was μm.

Comparative Example 3 Polymer (1) synthesized in Example 1 (1) was dissolved in methyl cellosolve to a concentration of 15% by weight, and coated on a silicon wafer with a dry film thickness of 0.5 μm using a spin code method. X-ray irradiation and development were carried out in the same manner as in Example 3, and the remaining film rate and resolution were examined. Although X-rays were irradiated to a dose of 500 mJ/cT1, the polymer was dissolved during development and no pattern could be obtained.

[Effect of the invention] The polymer having a propargyl group, etc. and a sensitizing group in the side chain used in the present invention has a sensitizing group in the molecule, so there is no possibility that the sensitizer will precipitate in the solution or during film formation. It is possible to form a uniform film without any oxidation, and an effective sensitizing effect can be obtained without sublimation of the sensitizer.

Further, a polymer obtained by halogenating a polymer having a propargyl group or the like in a side chain can efficiently undergo a crosslinking reaction when irradiated with radiation.

The radiation-sensitive polymer composition of the present invention can form fine resist patterns with high precision and high sensitivity, so it can be used in semiconductor integrated circuits, liquid crystal substrates, printing plates, television shadow masks, etc., which require particularly high resolution. It can be suitably used as a negative resist used in the production of products such as.

Claims (2)

[Claims] (1) A radiation-sensitive polymer composition characterized by containing a polymer having a propargyl group and/or a substituted propargyl group and a sensitizing group in its side chain. (2) A radiation-sensitive polymer composition characterized by containing a polymer obtained by halogenating a polymer having a propargyl group and/or a substituted propargyl group in its side chain.